ABSTRACT
Optics of materials could be understood as a reaction of atoms, molecules, or solids with the external electromagnetic radiation. This reaction is described in terms of different kinds of excitations, e.g., appearance of additional induced polarization due to electron transitions between available energy states, generation of lattice vibrations, and electron-hole pairs. This chapter presents an introduction to the basics of electron energy structure and the theory of optical functions of nanomaterials and focuses on the physical nature of phenomena.
